Field of the Invention
The present invention relates to a method for decoding moving pictures in intra prediction mode, and more particularly, to the method for generating a prediction block similar to an original image by adaptively generating and filtering reference pixels of a current block.
Discussion of the Related Art
Many digital video compression techniques have been proposed to efficiently transmit a video signal at a low data rate with high video quality. The video compression techniques include H.261, Moving Picture Experts Group-2/H.262 (MPEG-2/H.262), H.263, MPEG-4, Advanced Video Coding/H.264 (AVC/H.264), etc. These compression techniques involve Discrete Cosine Transform (DCT), Motion Compensation (MC), quantization, entropy coding etc.
To keep high video quality, a large amount of data is taken for video coding. However, an available data rate for transmitting coded data is limited because of a limited allowed bandwidth for video data transmission. For example, a data channel of a satellite broadcasting system or a data channel of a digital cable TV network transmits data typically at a Constant Bit Rate (CBR).
In this context, video coding schemes have been proposed to achieve high video quality, while minimizing implementation complexity and a transmission data rate.
For example, the H.264/AVC standard offers intra-prediction coding in a spatial area using adjacent pixels. Determining adjacent pixels to be used is important to improvement of coding efficiency. For this purpose, the optimum direction to be used for the intra-prediction is determined and a predicted value of a pixel to be encoded is calculated using adjacent pixels corresponding to the optimum direction.
However, as prediction blocks are increased diversified in size, a plurality of adjacent reference blocks are highly likely to exist for a current block. In this case, a difference of pixel values may be generated between reference pixels at both boundaries of the reference blocks. If intra-prediction is performed using the reference pixels, residual blocks obtained after the generation of prediction blocks may contain many high-frequency components. As a consequence, coding efficiency is decreased.